This invention relates to ion-exchange and filter water systems and has particular reference to an improved method and means for controlling the flow of water and regenerative fluids through an ion-exchange resin bed, in such systems.
In ion-exchange water treatment systems which employ beds of synthetic resin for removing hardness factors, iron and turbidity from water supplied thereto, it has been the practice to recondition or regenerate the bed following a period of service with the use of brine which, in somewhat diluted condition is forced downwardly through the bed, flowing in the same direction through the bed as does water during the service cycle of operation. Water treatment systems which operate in the manner outlined above have certain undesirable characteristics which are especially manifest when used for treating water high in iron content. The downward flow of the regenerating solution causes iron oxide to accumulate and become trapped in the lower regions of the resin bed, thereby necessitating complete removal of the bed for cleaning purposes at frequent intervals. Another disadvantage of former systems is that the diluted brine which reaches the mineral bed is much less efficient for rejuvenating the bed than is the full strength, concentrated brine or regenerants which act upon the resins or mineral in the system of the present invention.
Among the objects of the present invention is to provide an improved system for regenerating the mineral bed after a period of service whereby the minerals are restored to a higher degree of ion-exchange efficiency, the time required for the regeneration process is reduced, iron oxide particles are not retained and permitted to grow to the point where they clog the mineral bed, and the degree of salinity of the regenerative brine does not vary in marked degree with changes in the pressure of the water supply.
Yet another object of the invention is to provide for the use of treated water for the makeup of the brine solution, the treated water being introduced into the brine tank in such a way that the salt particles act as a filter for the saturated brine solution as it passes through the salt bed and to the mineral bed, whereby to prevent the entry of sand and other undesirable non-soluables that are normally found in various grades of salt, from entering into the treatment tank.
An important object of the invention is to draw concentrated brine upwardly through the mineral bed, counter-current to its service flow after which water pressure is applied to the effluent to cause its discharge to a drain which may be at a level above the treatment apparatus.
The foregoing and other objects and advantages are achieved by an improved control valve and brine induction provisions, which, under the dictages of a timer or sensor device and electrical solenoid valves controlled thereby, direct raw or untreated water downwardly through a bed of zeolites or other ion-exchange resins or minerals for a predetermined service period; or, with use of a device which senses the physical condition and hence the operating efficiency of the bed, cause regeneration of the bed to occur in a series of steps or cycles. The first of these is to draw concentrated brine or regenerant into the treatment tank, slowly, upwardly through the mineral bed. Following the brining operation, an upflow fast rinse cycle and an upflow washing cycle occur, and finally a fast down-flow rinse of the bed to remove all traces of regenerant solution and any turbidity of iron deposits in the mineral bed where the iron bearing waters are treated. Therefore the system is restored to the normal service cycle wherein the raw water is caused to flow downwardly through the regenerated mineral bed.